/*  Copyright 2011 AIT Austrian Institute of Technology
*
*   This file is part of OpenTLD.
*
*   OpenTLD is free software: you can redistribute it and/or modify
*   it under the terms of the GNU General Public License as published by
*    the Free Software Foundation, either version 3 of the License, or
*   (at your option) any later version.
*
*   OpenTLD is distributed in the hope that it will be useful,
*   but WITHOUT ANY WARRANTY; without even the implied warranty of
*   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
*   GNU General Public License for more details.
*
*   You should have received a copy of the GNU General Public License
*   along with OpenTLD.  If not, see <http://www.gnu.org/licenses/>.
*
*/

/*
 * VarianceFilter.cpp
 *
 *  Created on: Nov 16, 2011
 *      Author: Georg Nebehay
 */

#include "VarianceFilter.h"

#include "IntegralImage.h"
#include "DetectorCascade.h"

using namespace cv;

namespace tld
{
    VarianceFilter::VarianceFilter()
    {
        enabled = true;
        minVar = 0;
        integralImg = NULL;
        integralImg_squared = NULL;
    }

    VarianceFilter::~VarianceFilter()
    {
        release();
    }

    void VarianceFilter::release()
    {
        if (integralImg != NULL) delete integralImg;

        integralImg = NULL;

        if (integralImg_squared != NULL) delete integralImg_squared;

        integralImg_squared = NULL;
    }

    float VarianceFilter::calcVariance(int *off)
    {
        int *ii1 = integralImg->data;
        long long *ii2 = integralImg_squared->data;

        float mX = (ii1[off[3]] - ii1[off[2]] - ii1[off[1]] + ii1[off[0]]) / (float)off[5]; //Sum of Area divided by area
        float mX2 = (ii2[off[3]] - ii2[off[2]] - ii2[off[1]] + ii2[off[0]]) / (float)off[5];
        return mX2 - mX * mX;
    }

    void VarianceFilter::nextIteration(const Mat &img)
    {
        if (!enabled) return;

        release();

        integralImg = new IntegralImage<int>(img.size());
        integralImg->calcIntImg(img);

        integralImg_squared = new IntegralImage<long long>(img.size());
        integralImg_squared->calcIntImg(img, true);
    }

    bool VarianceFilter::filter(int i)
    {
        if (!enabled) return true;

        float bboxvar = calcVariance(windowOffsets + TLD_WINDOW_OFFSET_SIZE * i);

        detectionResult->variances[i] = bboxvar;

        if (bboxvar < minVar)
        {
            return false;
        }

        return true;
    }
} /* namespace tld */
